What happens if there is a fuel supply interruption to the APU?

When there is a fuel supply interruption to the APU, the most critical consequence is that the APU will experience a shutdown, leading to the loss of both electrical and pneumatic support. The APU relies on a continuous fuel supply to function properly; without it, the combustion process halts. As a result, all systems powered by the APU, including electrical systems and pneumatic pressure for starting engines and other pneumatic functions, will be affected immediately once the fuel supply is cut off. This loss of functionality underscores the importance of a reliable fuel supply for the overall operation of the APU in aircraft systems.